Use thefitmap.co.uk for an abdominal workout for your abs that teaches you to isolate the muscle set. Abdominal workouts actually target a set of three main muscles, the rectus abdominis, the obliques and the transversus abdominis.
When you do your abdominal workout, the rectus abdominis part of the abdominal wall is the long pair of muscles and is most often referred to as the 'six pack'. For productive abdominal workouts you need to know there are three tendinous intersections that divide it into the segments you can see provided your body fat is low enough.
This abdominal/ab muscle has the job of flexing and rotating the lumbar region of your spinal column. It also serves to hold the ribs in place and stabilizes the pelvis during walking. As these are the main muscles in your abdominal workout when you perform standard abdominal crunches, they are usually pretty strong in most people.
The oblique muscles are the largest of the three and run in the downwards direction from the side to the middle. If you were to take your hands and put them in your pockets, the direction your fingers point is the direction these muscle fibres run. When they act together they aid the rectus abdominis muscle with the flexing of the vertebral column. They also serve, as a pair, to rotate the trunk and perform lateral back flexion.
The transverse abdominis is the deepest muscle and runs horizontally underneath the more superficial rectus abdominis. Its job is to compress the abdominal contents and help maintain stability. It also plays a role when a woman goes into labour.
The great thing about these muscles is that whenever you perform an exercise or an everyday activity for that matter you will be working them. Those who have weak muscles are more prone to experiencing lower back pain as since they are always being called upon, if they are not strong enough to do their job your back will move out of alignment thus causing problems.
So make sure you dedicate some portion of your workout strictly to these three muscles and then also remember to contract them while performing the rest of your program for additional training.